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Reading Selection, Lesson 17

The Case of the Unidentified Ink

Among the kinds of work that forensic scientists do is to help solve crimes by using a wide range of scientific techniques to gather evidence. Chromatography is one important technique that they use to catch criminals. In this inquiry, you will need to place yourself in the role of just such a scientist.

Exhibit A shows a check with a signature on it. Is the signature on the check a forgery? Was the check written by the owner or someone else?

There are three suspects in this case, each of whom uses a different pen. The only way to find out who signed the check is to analyze the ink in the signature and compare it with the ink in the pens handed over as evidence (Exhibits B, C, and D).

Pen B belongs to the owner of the checkbook, pen C belongs to a notorious criminal, and pen D belongs to a teller at the bank. Your lab assistant has already extracted some ink from the signature on the check and placed a spot of it on a piece of chromatography paper.

Who wrote the check? Was a crime committed?

Illustration of

Exibit A: is this check a forgery?










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